OK...
I have both an SGS6 and an SGS6 Edge. ( Got the Edge first.....didn't really like the 'edge' thing and bought a non-Edge version).
I've now tried both in the Gear VR. The Gear VR *seems* to look better with the regular SGS6. In the Edge model there was subtle colour sifts in the pixels toward the edge of the screen.....that don't seem to be there in the non-Edge version of the phone.
Also: Apps!
If you get a chance, install the "Vrse" app. It has some awesome VR videos. I watched the U2 video, the "Evolution of Verse" video and the "Take Flight" video. They were all awesome. Seriously...and for U2 and Take Flight videos, you have to be either standing up or sitting on a swivel chair because you miss out on 75% of the content if you aren't spinning around looking at everything.
I also installed "NextVR". The content is thin.....but the talk by the Oculus guy, Brendan, and Mark Zuckerberg is great. It's like you're sitting right there a the foot of the stage......in 3D, of course.
The "Flickr" app is worth installing. They have a good selection of 360 photos from places all over the world.